JP2963772B2 - Photosensitive resin composition - Google Patents

Description

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a dry film photoresist for circuit design of a printed circuit board (hereinafter referred to as “PCB”).
The present invention relates to a photosensitive resin composition useful for producing resist).

Description of the Prior Art Usually, a dry film photoresist is formed by coating a base resin with a photosensitive resin composition mixed with an organic solvent and then drying, and then laminating a protective film on the dried photoresist film. Manufacturing. To manufacture PCBs, such dry film photoresists are laminated with copper foil using a laminator or uniformly coated on a copper-coated epoxy sheet. For this purpose, the dry film photoresist is first applied to the copper layer together with the base film after stripping off the protective film. A desired circuit (photo-tool) is adhered to the base film,
Exposure with UV light. As a result, the irradiated portion is cured, while the unexposed portion remains uncured. Thereafter, when the base film is removed and the uncured portion is removed from the substrate using a developing solution, the cured portion remains to form a circuit.

The main characteristics required for such a dry film photoresist include a high developing speed, flexibility of an exposed film, and chemical resistance to plating chemicals.

Of the components constituting the photosensitive resin composition, the photopolymerizable monomer has a very large effect on such characteristics, and therefore, great care should be taken in selecting the photopolymerizable monomer.

It is well known that increasing the degree of curing of a photosensitive resin improves chemical resistance. High degrees of cure can be achieved by using low molecular weight photopolymerizable monomers. Representative examples of low-molecular weight photopolymerizable monomers include ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, pentaerythritol triacrylate, trimethylolpropane trimethacrylate, ethoxylated trimethylolpropane trimethacrylate, and propoxylated trimethylolpropane triacrylate. Methacrylate,
There are such things as hydroxydimethacryloxypropane.

When a large amount of low molecular weight monomer is used, the number of reactive terminal groups of the monomer increases, thereby increasing the space in the photosensitive resin composition. The greater the space, the easier the developer penetrates and the faster the development speed.However, excessive curing due to an increase in the number of reactive terminal groups causes the film to become fragile, and the flexibility of the film increases. descend.

Photopolymerizable monomers containing phenyl groups are used to impart good chemical resistance to the photopolymerizable resin. Typical examples of phenyl group-containing photopolymerizable monomers include 2,2.
2-bis [(4-acryloxydiethoxy) phenyl]
Some have bisphenol A in the molecule, such as propane and 2,2-bis [(4-methacryloxydiethoxy) phenyl] propane. When such a phenyl group-containing monomer is used in a large amount, the penetration of the weak alkaline aqueous solution is delayed, which adversely affects the developing speed.

In order to increase the development speed, a photopolymerizable monomer accompanied by an ethylene glycol unit may be added. However, as mentioned above, the use of low molecular weight monomers with low ethylene glycol units makes the membrane fragile. On the other hand, the photopolymerizable monomer having a large amount of ethylene glycol units has the property of dissolving in water, thereby increasing the developing speed, maintaining the proper curing density, and increasing the toughness of the film after exposure. However, the plating chemical resistance is significantly reduced. As will be described in detail later, plating chemical resistance can be improved by using a combination of a monomer accompanying ethylene glycol and a monomer accompanying bisphenol A, but each monomer alone is not sufficient.

The flexibility of the dry film after exposure largely depends on the degree of curing and the structure of the monomer. For example, if there are too many curable monomers in the composition, the curing will be large, resulting in poor flexibility. On the other hand, if the amount of the curable monomer is small, the curing will be low, and as a result flexibility will increase, but plating chemical resistance will be poor. In the manufacture of a PCB, the flexibility of a film cured by exposure greatly affects the ability of the cured film to fill holes after development in the manufacture of a printed circuit board, that is, tentability. If the flexibility is good, the tenting ability is improved, and as a result, the productivity is improved.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems in the prior art, and to provide a useful photosensitive resin composition for producing a photoresist having a high developing speed, being very flexible, and having excellent plating chemical resistance. Is to provide.

According to the present invention, the object is to provide a photosensitive resin composition containing a photopolymerizable monomer, a thermoplastic polymer binder and a photoinitiator, wherein the photopolymerizable monomer is at least one water-soluble monomer. And at least one
At least two unsaturated reactive groups, the content of the water-soluble monomer is 3 to 15% by weight based on the solid content of the composition, The reactive group of the polymerizable monomer is calculated by the following formula I:
This can be attained by providing a photosensitive resin composition characterized in that the content is 0.5 to 1.5 mol per 1 kg of the solid content of the composition.

Here, # M is the total amount of solids kg commonplace Symbol reactive groups of the composition, M _i is the number of moles of solids per kg photopolymerizable monomer i in the composition, N _i photopolymerization And k is the total number of photopolymerizable monomers in the composition.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, a water-soluble photopolymerizable monomer with an ethylene group is used to increase the flexibility of the cured part. Although not limited thereto, examples of the water-soluble photopolymerizable monomer include 2,2-bis [(4-acryloxypolyethoxy) phenyl] propane and 2,2-bis having 25 to 40 ethylene glycol repeating units. Screw [(4-
Methacryloxypolyethoxy) phenyl] propane and polyethylene glycol dimethacrylate having 8 to 15 ethylene glycol repeating units exhibit good properties.
Specifically, if the number of ethylene glycol repeating units is large, the water solubility increases, so if the number of photopolymerizable monomers increases,
Although the water solubility is improved, the plating chemical property is reduced.
On the other hand, if the number of ethylene glycol repeating units is reduced, the plating chemical property is improved, but the developability and flexibility are poor.

According to the present invention, a water-insoluble photopolymerizable monomer can be used. Specific examples of the water-insoluble photopolymerizable monomer include ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, pentaerythritol trimethacrylate,
Trimethylolpropane trimethacrylate, ethoxylated trimethylolpropane trimethacrylate, propoxylated trimethylolpropane trimethacrylate, polypropylene glycol dimethacrylate, hydroxydimethacrylate, 2,2-bis [(4-acryloxydiethoxy) phenyl] propane, 2,2-bis [(4-acryloxypolyethoxy) phenyl] propane, 2,2-bis [(4-methacryloxydiethoxy) phenyl] propane, 2,2-bis [(4-methacryloxypolyethoxy) Phenyl] propane, or a mixture of two or more thereof. Of course, the invention is not limited to such compounds, and analogs thereof can be used.

To increase the flexibility of the dry film, the total amount of reactive end groups (#M) of the photopolymerizable monomer, when calculated using Formula I, is based on the solids content of the composition of the present invention.
In the range of 0.5 mol / kg to 1.5 mol / kg, more preferably 0.
It should be in the range of 8 mol / kg to 1.2 mol / kg.
If #M is less than 0.5 mol / kg, the dry film exhibits weak chemical resistance. On the other hand, when #M exceeds 1.5 mol / kg, the flexibility of the dry film is reduced, and the tenting ability is reduced.

In addition to the photopolymerizable monomer, the photosensitive resin composition for a dry film photoresist should include a polymer binder, a photoinitiator, and other essential components. In some cases, additives such as an adhesion promoter, a thermal polymerization inhibitor, a dye and the like can be added.

The binder polymer has a weight average molecular weight (M _w ) of 10,000.
A 00～400,000, glass transition temperature (T _g) 40 to 130 ° C.
The preferred content is 50 to 80% by weight based on the solid content of the photosensitive resin composition.

Such binder polymers can be made from addition polymerizable monomers, such as methyl acrylic acid, butyl acrylic acid, alkyl acrylic acids such as methyl methacrylic acid, alkyl methacrylic acids and styrene and Esters such as styrene derivatives, acrylates and methacrylates may be used. To support developability in aqueous alkaline solutions,
It is preferable to add an acid component such as acrylic acid, methacrylic acid, maleic acid, crotonic acid and the like.

Photopolymerization initiators suitable for the composition of the present invention include substituted or unsubstituted polynuclear quinones such as 2-ethylanthraquinone, 2-t-butylanthraquinone, octamethylanthraquinone, 1,2-benzanthraquinone, Three
-Benzanthraquinone, 2-phenylanthraquinone, 2,3-diphenylanthraquinone, 1-chloroanthraquinone, 2-chloroanthraquinone, 2-methylanthraquinone, 1,4-naphthaquinone, 9,10-phenanthraquinone, 1,2- Dimethylanthraquinone and aromatic ketones such as benzophenone, Michler's ketone (4,4-bisdimethylaminobenzophenone), 4,4-bisdiethylaminobenzophenone, 4-methoxy-4-
As bisdimethylaminobenzophenone, benzoin and benzoin ethers, for example, benzoin methyl ether, benzoin ethyl ether, benzoin phenyl ether, methyl benzoin, ethyl benzoin, and 2,4,5
-Triarylimidazole dimers and the like may be used.
Further, substituted or unsubstituted thioxanthones such as 2-chlorothioxanthone and 2,4-diethylthioxanthone, and aliphatic tertiary amines such as methyldiethanolamine or aromatic tertiary amines can also be used.

Such photoinitiators activated by light may be used alone or in combination of two or more. Such a photoinitiator is preferably added in an amount of 0.5 to 10% by weight based on the solid content of the photoresist composition. If too little photoinitiator is used, it will not be sufficiently cured by light. If the amount of the photoinitiator exceeds 10% by weight, the photoinitiator becomes sensitive to light and becomes difficult to work.

Other additives that can be added to the photosensitive resin composition used as a dry film photoresist include an adhesion promoter that increases the adhesion to the copper plate, a dye, and a thermal polymerization inhibitor. Benzotriazole or the like can be used as an adhesion promoter, and Victoria Blue,
Methylene blue, crystal violet, malachite green, and the like can be used. As the thermal polymerization inhibitor, hydroquinone, hydroquinone monomethyl ether, t
-Butyl catechol and the like can be used.

In general, a dry film photoresist is manufactured by coating a photosensitive resin composition mixed with an organic solvent on a base film, drying the coating, and laminating a protective film on the dried photoresist layer.

The base film may be durable at 100 ° C. or higher and transparent. For example, a polyester film, a nylon film, a polyimide film, a polycarbonate film and the like can be used, and a particularly preferable one is a polyethylene terephthalate film.

The protective film is used to protect the photoresist layer from foreign substances and prevent the dry film photoresist from sticking to each other when manufactured in a roll state. Primarily, a polyolefin-based film such as polyethylene or polypropylene is used.

The dry film photoresist can be uniformly laminated on a copper plate (or an epoxy laminate coated with copper foil) using a laminator during the manufacture of a printed circuit board. At this time, the protective film is removed, and the photoresist layer is attached to the copper plate together with the base film. When a desired circuit (phototool) is placed on and adhered to the base film and then irradiated with ultraviolet light, the light-receiving portion (exposed portion) is cured, and the other portion remains uncured. When the developer is sprayed onto the substrate after the base film is removed, the uncured portion is removed by the developer, and the cured portion remains on the substrate to form a circuit.

1,1, to develop dry film photoresist
An organic solvent such as 1-trichloroethane or a weak alkaline aqueous solution such as an aqueous sodium carbonate solution is used. Recently, it is common to use dry film photoresists that can be developed with weak alkaline aqueous solutions. The substrate on which the circuit is formed is then manufactured into a PCB through plating, etching, and peeling processes. A photosensitive resin composition that can be developed with a weak alkaline aqueous solution has good plating chemical resistance in a general acidic copper plating solution, but the chemical resistance in a solder plating solution is greatly affected by the composition.

Hereinafter, the present invention will be described in more detail by way of non-limiting examples. In the composition components of the following Examples and Comparative Examples, * represents a water-soluble photopolymerizable monomer and ** represents
Represents a water-insoluble photopolymerizable monomer.

Example 1 Photosensitive resin composition Methyl methacrylic acid (50%) /
Ethyl acrylic acid (30%) / methacrylic acid (20%) copolymer was used in an amount of 65 parts by weight. This polymer binder is GPC (w
ater, column: Shodex KF Series, standard sample: standard po
Lystyrene, weight average molecular weight measured using a RI detector) (M _W) was approximately 70,000. The photopolymerizable monomer has a molecular weight of 1,684 and an average number of ethylene glycol repeating units per molecule (hereinafter referred to as “▲ ▼”) of 30 ^* 2.
2- bis [(4-methacryloxy polyethoxy) phenyl] propane 12 parts by weight, 8 parts by weight of ^** tetraethylene glycol dimethacrylate with a molecular weight 330 and molecular weight
^** , 7 parts by weight of ethoxylated trimethylolpropane triacrylate. 4 parts by weight of benzophenone, 0.5 parts by weight of Michler's ketone, 0.05 parts by weight of Victoria Blue, 0.05 parts by weight of hydroquinone monomethyl ether, 0.5 parts by weight of benzotriazole, and 100 parts by weight of methyl ethyl ketone were added to the mixture, mixed uniformly, and reacted on a solid basis. Total number of functional end groups (#M) 1.15 mol / kg
Was produced.

The obtained composition was applied on a 25 μm-thick polyethylene terephthalate film support and dried at 80 ° C. for 5 minutes to obtain a 40 μm-thick photosensitive film. A polyethylene film having a thickness of 30 μm was laminated on the photosensitive film using a rubber roll.

Comparative Examples I and II The procedure of Example I was repeated using the following photopolymerizable monomers.

Comparative Example I: Composition of photopolymerizable monomer ^* 2,2-bis [(4-methacryloxypolyethoxy)
Phenyl] propane _{(Mw = 1.684, N EG =} 30) 5 parts by weight ^** tetraethylene glycol dimethacrylate (Mw
= 330) 7 parts by weight ^** Ethoxylated trimethylolpropane triacrylate (Mw = 428) 15 parts by weight Total amount of reactive terminal groups 1.58 mol / kg Comparative Example II: Composition of photopolymerizable monomer ^* 2,2 bis [( 4-methacryloxypolyethoxy) phenyl] propane (Mw = 1,684, N _EG = 30 15 parts by weight ^** 2,2-bis [(4-methacryloxypolyethoxy) phenyl] propane (Mw = 804, N _EG = 10 ) 12 parts by weight ^** polypropylene glycol diacrylate (Mw =
808) 7 parts by weight Total amount of reactive terminal groups (#M) 0.4 mol / kg Example II As a photosensitive resin composition, methyl methacrylic acid (40%) / 2-ethylhexylacrylic acid (Mw = 50,000) (20
%) / Styrene (20%) / methacrylic acid (10%) / acrylic acid (10%) copolymer 65 parts by weight, molecular weight of 1,684, N _EG is a 30 ^* 2,2-bis [(4 -Methacryloxyethoxy) phenyl] propane 8 parts by weight, molecular weight 804
And _NEG is 10, ^** 2 parts by weight of 2,2-bis [(4-methacryloxypolyethoxy) phenyl] propane, Mw
= 536 ^** 8 parts by weight of polypropylene glycol diacrylate, ^** 3 parts by weight of hydroxydimethacryloxypropane, 4 parts by weight of benzophenone, Michler's ketone
From 0.5 parts by weight, 0.05 parts by weight of Victoria Blue, 0.5 parts by weight of benzotriazole, 0.05 parts by weight of hydroquinone methyl ether and 100 parts by weight of methyl ethyl ketone, a photosensitive resin composition having a total reactive terminal group (#M) of 0.88 was produced. The same procedure as in Example 1 was repeated except that it was used.

Comparative Example III The procedure of Example I was repeated using the following photopolymerizable monomer.

Composition of photopolymerizable monomer ^* 2,2-bis [(4-methacryloxypolyethoxy)
Phenyl] propane (Mw = 1,684, _NEG = 30) 2 parts by weight ^** 2,2-bis [(4-methacryloxypolyethoxy) phenyl] propane (Mw = 804, _NEG = 10) 10 parts by weight ^** Ethoxylated trimethylolpropane triacrylate (Mw = 428) 8 parts by weight ^** polypropylene glycol diacrylate (Mw =
808) 7 parts by weight Total amount of reactive end groups (#M) 1.04 mol / kg Example III The procedure of Example 1 was repeated using the following photosensitive resin composition {}.

Photosensitive resin composition Methyl methacrylate (40%) / phenoxyethyl acrylic acid (40%) / methacrylic acid (10%) / acrylic acid (10%) copolymer (Mw = 80,000) 5 parts by weight ^* 2,2- Bis [(4-methacryloxypolyethoxy)
Phenyl] propane (Mw = 1,684, _NEG = 30) 8 parts by weight ^* polyethylene glycol dimethacrylate (Mw = 53
6, N _EG = 9) 5 parts by weight ^* 2,2-bis [(4-methacryloxypolyethoxy)
Phenyl] propane (Mw = 804, _NEG = 10) 7 parts by weight ^** polypropylene glycol diacrylate (Mw =
536) 5 parts by weight ^** Ecoxylated trimethylolpropane triacrylate (Mw = 428) 2 parts by weight Benzophenone 4 parts by weight Michler ketone 0.5 parts by weight Diamond green GH 0.05 parts by weight Benzotriazole 0.5 parts by weight Hydroquinone monomethyl ether 0.05 parts by weight Methyl ethyl ketone 100 parts by weight Part Total amount of reactive end groups (#M) 0.8 mol / kg Examples IV and V and Comparative Examples IV and V The procedure of Example 3 was repeated using the following photopolymerizable monomers.

Example IV: Composition of photopolymerizable monomer ^* polyethylene glycol dimethacrylate (Mw = 53
6, N _EG = 9) 12 parts by weight ^** polypropylene glycol diacrylate (Mw =
536) 8 parts by weight ^** ethoxylated trimethylolpropane triacrylate (Mw = 428) 7 parts by weight Total amount of reactive terminal groups (#M) 0.81 mol / kg Example V: Composition of photopolymerizable monomer ^* polyethylene glycol di Methacrylate (Mw = 73
6, N _EG = 14) 10 parts by weight ^** propoxylated trimethylolpropane triacrylate (Mw = 470) 7 parts by weight ^** 2,2-bis [(4-methacryloxypolyethoxy) phenyl] propane (Mw = 804) 10 parts by weight Total amount of reactive terminal groups (#M) 1.0 mol / kg Comparative Example IV: Composition of Photopolymerizable Monomer ^** 2,2-bis [(4-methacryloxypolyethoxy) phenyl] propane (Mw = 804, N _EG = 10) 12 parts by weight ^** tetraethylene glycol dimethacrylate (Mw
= 330) 5 parts by weight ^** Propoxylated trimethylolpropane triacrylate (Mw = 470) 10 parts by weight Total amount of reactive terminal groups (#M) 1.28 mol / kg Comparative Example V: Composition of photopolymerizable monomer ^* 2 , 2-bis [(4-methacryloxypolyethoxy)
Phenyl] propane _{(Mw = 1.684, N EG =} 30) 7 parts by weight ^* of polyethylene glycol dimethacrylate (Mw = 73
6, _NEG = 14) 7 parts by weight ^** trimethylolpropane triacrylate (Mw =
296) 8 parts by weight ^** 1,6-hexanediol dimethacrylate (Mw = 25
4) 5 parts by weight Total amount of reactive end groups (#M) 1.52 mol / kg Analysis The developing speed, tenting property and plating chemical resistance of the above Examples and Comparative Examples were measured by the following methods. The measurement results are presented in Table 1 below.

1.Development speed Use a laminator on a copper plate polished with a brush.
The photosensitive film was laminated at a temperature of 1 ° C., a pressure of 1 atm and a speed of 1 m per minute. This was maintained at room temperature for 15 minutes, and after the surface temperature reached room temperature, the development time was measured using a developing device.
The laminator used was a product of Western Magnum (Western Magnum, XRL 240) and the developer was a product of Chemcut (Chemcut. Model 413W). The developing solution used was a 1% aqueous solution of sodium carbonate heated to 30 ° C., and was sprayed from a nozzle at a pressure of 1.5 atm.

2. Tenting properties To test the tenting properties, which is a measure of the flexibility of the film, a laminator was used on a copper plate with 48 holes each with a diameter of 1, 2, 3, 4, 5, 6, and 6.3 mm. Then, dry films were laminated on both sides. Ten copper plates were used per sample. After cooling the copper plate to room temperature,
Exposure was for 15 seconds. The exposure equipment used was Colite (Coligh
t) DMVL 1330. After exposure, development was repeated twice for twice the development time measured previously, and the number of torn holes was counted.

3. Plating resistance After forming a circuit of 0.3mm interval on the copper plate by the same method as the measurement of the tenting property, it is processed as follows, and is peeled off from the copper plate in the final solution (4th solution). Time was observed.

i. Sulfuric acid treatment: 10% sulfuric acid aqueous solution, immersion for 30 minutes at room temperature ii. Water washing: normal temperature, 5 times washing for 10 seconds each iii. Dipping with 20% aqueous solution of fluoroboric acid for 30 seconds, room temperature iv. Immersion in aqueous solution, normal temperature When compared with Comparative Example I and Comparative Example II, Example I has the same developing speed, but is superior in the breaking rate of the tenting hole and the plating chemical resistance.

In Comparative Example III, the developing speed was about 50% lower than that in Example II, and the breaking ratio of the tenting holes was as high as 4%.

As can be clearly seen from Table 1, the composition according to the present invention is useful for preparing a photoresist having excellent development speed, flexibility and plating chemical resistance.

It is to be understood that the present invention has been described in an illustrative manner and that the terms used are intended to be illustrative rather than restrictive.

The present invention can be variously modified and changed from the above-described technology. Thus, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H05K 3/06 H05K 3/06 H (72) Inventor Park Ki-Jin South Korea 614-054 Busan Busanjin-Kang Yangjun-4-Don 107-18 ( 56) References JP-A-61-228007 (JP, A) JP-A-1-159637 (JP, A) JP-A-7-146550 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , (DB name) G03F 7/027 C08F 290/06 C08F 299 / 02,2 / 50 C08L 71/00

Claims (4)

(57) [Claims] 1. A photosensitive resin composition containing a photopolymerizable monomer, a thermoplastic polymer binder and a photoinitiator, wherein (1) the photopolymerizable monomer comprises at least one water-soluble monomer, One water-insoluble monomer;
(2) both have two or more unsaturated reactive groups, (3) the content of the water-soluble monomer is 3 to 15% by weight based on the solid content of the composition, (4) The reactive group of the entire photopolymerizable monomer, when calculated by the following formula I, is 0.5 to 1.5 / kg of the solid content of the composition.
A photosensitive resin composition characterized in that it is a mole. Here, # M is the total amount of solids 1kg commonplace Symbol reactive groups of the composition, M _i is the number of moles of solids 1kg per photopolymerizable monomer i in the composition, N _i photopolymerization And k is the total number of photopolymerizable monomers in the composition. 2. The water-soluble photopolymerizable monomer according to claim 1, wherein the total number of ethylene glycol units is 25 to 40.
A photosensitive resin composition characterized by being 2,2-bis [(4-acryloxypolyethoxy) phenyl] propane or 2,2-bis [(4-methacryloxypolyethoxy) phenyl] propane. 3. The water-soluble photopolymerizable monomer according to claim 1, wherein the total number of ethylene glycol units is 25 to 40.
2,2-bis [(4-acryloxypolyethoxy) phenyl] propane or 2,2-bis [(4-methacryloxypolyethoxy) phenyl] propane and polyethylene glycol diacrylate having 8 to 15 ethylene glycol units Or a mixture of polyethylene glycol dimethacrylate. 4. The method according to claim 1, wherein the water-insoluble photopolymerizable monomer is ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, pentaerythritol trimethacrylate, trimethylolpropane trimethacrylate. , Ethoxylated trimethylolpropane trimethacrylate,
Propoxylated trimethylolpropane trimethacrylate, polypropylene glycol dimethacrylate, hydroxydimethacryloxypropane, 2,2-bis [(4
-Acryloxydiethoxy) phenyl] propane, 2,2
-Bis [(4-acryloxypolyethoxy) phenyl]
Propane, 2,2-bis [(4-methacryloxydiethoxy) phenyl] propane, 2,2-bis [(4-methacryloxypolyethoxy) phenyl] propane, or a mixture of two or more thereof Characteristic photosensitive resin composition.